Date: Fri, 17 Apr 1998 09:20:34 -0400 From: "Gary Palmer" <gpalmer@FreeBSD.ORG> To: Greg Hormann <ghormann@nix.kconline.com> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: FreeBSD and Sendmail Message-ID: <9061.892819234@gjp.erols.com> In-Reply-To: Your message of "Thu, 16 Apr 1998 20:16:08 CDT." <Pine.BSI.3.95.980416201320.5907B-100000@wawasee.read.indiana.edu>
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Greg Hormann wrote in message ID <Pine.BSI.3.95.980416201320.5907B-100000@wawasee.read.indiana.edu>: > % systat -iostat > (disk usage) > > % systat -vmstat > (interupt info may be useful) > > man systat for more info. Thanks for the hints (I already know systat :-) ), but the figures don't really account for idleness, just busyness. There is no measure of how much capacity is left in the drive to do i/o operations. (Believe me, I watch systat -v 1 like a hawk during performance tuning) The vmstat display basically shows the same ammount of info about the disks that iostat does, just differently. Stuff not available: - Number of queued tagged commands (if supported). This could give a rough indication of if the drive was busy or not. - Average seek time. The number of transactions/second (or seeks/sec) is nearly useless without this info. If he is having a lot of full platter seeks, the transaction rate will drop drastically, giving the impression that the disk is not the bottleneck. On the flip side, a lot of short seeks (in the same CG) could give the impression that the disk is nearly maxed out when infact it has more i/o capacity left. Of course, this figure is very difficult to get ... There is other stuff which would be nice to get out of the system to highlight bottlenecks, or potential bottlenecks, but I don't think that the person that spawned this thread has investigated the simple options, let alone the more complex ones. (I'm currently sorta responsible for a 360,000 user mail system running mainly on FreeBSD, so I have a rough idea what I'm talking about :) ) Gary -- Gary Palmer FreeBSD Core Team Member FreeBSD: Turning PC's into workstations. See http://www.FreeBSD.ORG/ for info To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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